Tube expander



Oct. 3, 1950 TUBE EXPANDER Filed Sept. 24, 1948 F. E. DUDLEY ETAL 2 Sheets-Sheet 1 INVENTOR 7 021 flDudJe y wam .padz WQQW ATTORNEY$ Oct 1950 F. E. DUDLEY ET AL 2,524,164

TUBE EXPANDER Filed Sept. 24, 1948 2 Sheets-Sheet 2 57.2? i K g5 g2 V V INVENTORS ATTORNEYS Patented Oct. 3, 1950 TUBE EXPANDER Frank E. Dudley, Philadelphia, Pa., and Harold K. Dudley, Chicago, Ill.

Application September 24, 1948, Serial No. 51,056

4 Claims. (Cl. 153-82) The present invention relates to tube expanders and processes of making the same.

A purpose of the invention is to facilitate the formation of roller slots in tube expander cages.

- the circumference and preferably of approximately the same width as the tube expander roller slot at the bottom of the slot, to insert a reversely tapered milling cutter through the hole, to translate the rotating cutter in the direction of the slot and then to remove the cutter through the same or a similar hole.

A further purpose is to drill a hole and then to produce a tube expander roller slot entirely from one set-up position of the tool with respect to the work.

A further purpose is to facilitate the setting of the collar with respect to the cage.

Further purposes appear in the specification and in the claims.

In the drawings we have chosen to illustrate a few only of the numerous embodiments in which 4 the invention may appear, choosing the forms shown from the standpoint of convenience in illustration, satisfactory operation and clear demonstration of the principles involved.

Figure 1 is a side elevation of a complete tube expander produced in accordance with the invention.

Figure 2 is a fragmentary central longitudinal.

section of a tube expander cage, mandrel and roller.

Figure 3 is a section of Figure 2 on the line 3-3.

Figures 4, 5 and 6 are side elevations of the tube in the characing the cage and milling cutter set up for'milling a slot.

In the drawings like numerals refer to like parts throughout.

Described in illustration but not inlimitation and referring to the drawings:

In the manufacture of heat exchangers such as condensers, boilers and the like, tube expanders are commonly used to roll tubes into liquidtight engagement with the tube sheet. Such expanders normally employ rolls held in the slots of a cage at suitable circumferential intervals, for example with three rollers around the circumference. Of course the number of rolls may vary with the size and other considerations.

The forming of the slots has been rather difficult and expensive. The difficulty is due to the combination of a number of factors. The slots in the cage which contain the rollers do not have parallel sides, but converge to a space at which the rollers will be held from leaving the slots. Furthermore, although the slots extend longitudinally of the cage, they are usually angularly positioned with respect to the cage, so that the matter of aligning the slots presents some difficulty.

The prior practice has been to set up the cage individually for each of the sides of the slot, and machine each side as by grinding at a particular set up, and then change the set up for machining the next side. The set up positions do not correspond with any feature of the geometry of the cage, but require indexing the cage at a position at which the side of the slot will be on the line of cut of the tool, while the radius of the cage through the middle of the slot is off to one side of the line of cut.

Difficulty has also been encountered due to the tendency of the rollers to wear rather rapidly in some cases and also to cause wear on the walls of the slot.

By the present invention the expense and trouble in machining the slots are greatly reduced, while the lubrication of the rollers is improved to a marked extent. In accordance with the invention an entire slot is machined from one set up position. Furthermore, the set up position places the diameter of the cage central of the slot at one position along the slot, thus simplifying the set up. The slot, after machining, also provides much better lubrication for the roller. The reduction in bearing surface due to the holes tends to reduce friction between the roller and the slot. v p

The present invention also facilitates the adjustment of the cage with respect to the collar. In tube rolling,'it is generally bad practice to expand the tube beyond or inside of the tube sheet, as this causes difiiculty in removing the .the collar remains stationary.

tube, and also tends to weaken the tube where it engages the inner edge of the tube sheet. In order to avoid such rolling of the tube inside the tube sheet, the collar must be adjusted with respect to the cage for each job. The proper gaging of the position of the collar has been troublesome in the prior art.

In accordance with the invention, a scale is provided on the cage, by which the collar can be adjusted without separate gages and with a minimum of trouble.

In accordance with the invention the tube expander 3o comprises a mandrel 3| surrounded by a cage 32 having circumferentially spaced slots 33 containing expander rollers 34'. The rear end of the cage is surrounded by a collar 35 which is internally threaded and engages threads 38 on the cage and is held at a predetermined position by a lock nut 31.

A scale 32' is provided longitudinally of the cage, and desirably stamped or etched therein.

By this scale, the proper position of the forward edge 35' of the collar is determined by moving the collar along the threads 36, and then tightening the lock nut 31.

The mandrel 3! consists of a shank 38 for chucking on the motor-driven tube roller, a shoulder portion 40, a gradually; tapered expander portion 4! which forces the rollers radially outlies in a cylindrical path which is to expand the;

tube. The forward end of the rollers is suitably abruptly pointed at 41, although this feature forms no part of the present invention. The rear ends of the rollers are filleted at 48.

The cage is tubular, having an internal bore .59 through which the mandrel passes. The forward nose of the cage is conveniently tapered at 5!.

The collar 35 has a forward portion 52 which is capable of surrounding the expander rollers when the collar is threaded forward to a sufiicient extent and of limiting the extent of out ward expansion of the rollers. The sleeve portion 52 is suitably rotatably mounted on the collar so that it can turn with the rollers while The rotatable mounting is a well known feature (see sleeve 21 5 of Brackett U; S. Patent 2,448,512) and may be ures 1, 4, 5, 6 and 9, although extending generally longitudinally. The slots converge as best seen in Figure 3. at 53, so that the outer circumferential edges 54 are much closer together than the inner circumferential. edges 55-. The outer circumferential edges. are placed closely enough together so thattheir space is less thanthe diameter of the rolls and thereby the rollers are retained in the slots.

The manufacture of the roller slots in accordance with the present invention will be best understood by reference to Figures 9 to 12. The cage is set up on a milling machine with the center line 56 of the slot along the path of travel (lateral feed) of a milling cutter 51, so that the milling cutter can out both sides of the slot simultaneously in a single forward or forward and backward translation. A hole 58 is drilled, having its center at the center line of the slot and preferably of a diameter which is about the same as the spacing of the slot at the inside of the cage. The diameter will normally be slightly larger than this maximum width of the slot. The position of the hole along the slot will vary in particular installations. For example, there may be a hole 58 at one end of the slot, as shown in Figures 1, l, 6 and 9 or there may be an additional hole 58 at the opposite end of the slot as shown in Figures 1 and 6, or there may be a hole 58 at some intermediate point such as the middle of the slot (Figures 5 and 6).

The milling cutter 51 has circumferential cutting edges 66 as best seen in Figures 7 and 8, and

has reversely taperedsides 6 1:, whose spacing and angle of: taper corresponds with the spacing and angle. of. taper of theI roller slots at a particular longitudinal position of the milling cutter with respect to the work. The milling cutter is inserted through the hole 58 (or 58 or 58 into the work; as best seen in Figures 9 and 10, the depth of'the milling cutter with respect to the work corresponding to the exact depth at which the-milling cutter will give the correct slot width when moved laterally. It is possible to insert the milling cutter too. deep initially and make a roughing cut, to be followed with a finish cutby the same-or a; different milling cutter inserted to the correct depth, but it has been found that in practice the entire slot can be made with a single out.

Once the'milling cutter is correctly adjusted aeto depth, it is-moved laterally along the path 52 of the slot until it has reached the position as shown in Figure 11 at the opposite endof the slot. It. will, of'eourse, be understood that if the milling cutter is inserted at some intermediate point; in the-slot it will be translated in both directions to cut the slot.

When the milling cutter has completed the cut as indicated-in Figure 11 it will bebrought to. a location of one of the holes as shown in Figure 12 and withdrawnthrough such hole. If it. is necessary tomove the milling cutter. back across the slot which has just been out as indicated in Figures 11 and 12. the milling cutter may or may not. be moved deeper into the work so that it will not cut on the reverse translation.

For many purposes it is. found that the most convenient arrangement is to provide two. holes 58 and 58' at opposite ends of the length of the slot, and then. to insert the milling cutter through one hole and translate to the opposite hole, Withdrawing through such opposite hole. It. will be understood, of course, that the speed of rotation ofthe milling cutter and the feed (translation) will vary with the particular material of the case,

the particular tool and the preference of the individual operator.

It has been found that the holes are of definite advantage in improving the lubrication and avoiding'wearand scoringof the rollers and the slot walls. The holes thus function as oil grooves to aid in carrying lubrication to the interfaces between the cage and the roller andbetween the roller and the tube. Oil-is ordinarily available around the mandrel. For this purpose the construction of Figure 6 or even the construction of Figure 5 offer advantages, since a hole is provided near the middle of the roller which is very vulnerable to wear. Thus it will be seen that the invention provides an advantage from the standpoint of machining of the grooves, and also a further advantage from the standpoint of service of the cage. Definitely improved service life is obtained, while at the same time the cost of production of the cage is markedly reduced.

A serious difliculty has been encountered in the rolling of various tubes through the tendency of flakes from the tubes to accumulate in the slots and clog the same, also increasing the wear on the rollers and slots. This difiiculty exists with steel and stainless steel tubes, but is more pronounced with copper, brass and cupronickel, and is very serious with aluminum tubes. The holes at the sides or ends of the slots provide reservoirs in which the flakes can collect and by which they can be removed to avoid clogging and to avoid wear.

In view of our invention and disclosure variations and modifications to meet individual whim or particular need will doubtless become evident to others skilled in the art, to obtain all or part of the benefits of our invention without copying the process and structure shown, and we, therefore, claim all such insofar as they fall within the reasonable spirit and scope of our claims.

Having thus described our invention what we claim as new and desire to secure by Letters Patent is:

1. In a tube expander, a tubular cage having a plurality of circumferentially spaced slots extending radially through the cage and also extending generally longitudinally and having their side walls converging radially outwardly, tapered rollers having straight sides positioned in said,

slots, and portions of said slots being circumferentially widened to provide radially extending openings adjacent said rollers for receiving flakes or lubricant.

2. In a tube expander, a tubular cage having a plurality of circumferentially spaced slots extending radially through the cage and also extending generally longitudinally and having their side walls converging radially outwardly, tapered rollers having straight sides positioned in said slots, and the end portions of said slots being 8 circumferentially widened to provide radially extending openings adjacent said rollers for receiving flakes or lubricant.

3. In a tube expander, a tubular cage having a plurality of circumferentially spaced slots extending radially through the cage and also extending generally longitudinally and having their side walls converging radially outwardly, tapered rollers having straight sides positioned in said slots, and the intermediate portions of said slots being circumferentially widened to provide radially extending openings adjacent said rollers for receiving flakes or lubricant.

4. In a tube expander, a tubular cage having a plurality of circumferentially spaced slots eX- tending radially through the cage and also extending generally longitudinally and having their side walls converging radially outwardly, tapered rollers having straight sides positioned in said slots, and the intermediate and end portions of said slots being circumferentially widened to provide radially extending openings adjacent said rollers for receiving flakes or lubricant.

' FRANK E. DUDLEY.

HAROLD K. DUDLEY.

REFERENGES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 883,589 Parry May 29, 1888 487,194 Mossberg Nov. 29, 1892 767,367 Westinghouse Aug. 9, 1904 1,044,333 Adams Nov. 12, 1912 1,102,993 Wiedeke July 7, 1914 1,412,278 Dixon 1 Apr. 11, 1922 1,596,262 Walker Aug. 17, 1926 1,800,991 Forst Apr. 14, 1931 2,448,512 Brackett Sept. '7, 1948 FOREIGN PATENTS Number Country Date 628,595 Germany Apr. 7, 1936 4,482 Great Britain Apr. 11, 1885 4,715 Great Britain Mar. 2, 1896 

